Engines historically have had solid rubber mounts to isolate engine vibration from the vehicle cabin and chassis, where the rubber naturally absorbed vibrations from the engine. However, in performance and high end cars, if rubber is too compliant, then certain vehicle maneuvers may cause high loads, and this may stress joints in the vehicle, for example in the exhaust system. Hence, tunable active engine mounts have been developed that may be controlled to change dampening characteristics depending on engine load.
As an example, the active engine mounts may be configured to be soft at engine idle to absorb undesired vibrations. However, at higher engine speeds, the active engine mounts may be configured to stiffen, to limit undesired engine motion, which may prevent stress on exhaust joints, for example. Accordingly, active engine mounts may achieve low noise, vibration, and harshness (NVH) at idle, and may further reduce NVH and prevent undesired stress at high loads.
For vehicles where a vehicle operator is typically operating the vehicle, the vehicle operator or other passengers in the vehicle may experience undesired NVH during certain vehicle conditions, which may result in the vehicle operator taking the vehicle to a repair shop such that a diagnosis can be made as to the source of the undesired NVH. However, there may be cases where a vehicle operator does not recognize the undesired NVH in a timely fashion to prevent vehicle complications arising from the undesired NVH. Furthermore, there may be instances, such as in the case of autonomously driven vehicles (AV), where a vehicle or passenger may not be present to observe undesired NVH. Thus, in such an example, as well as in examples where a vehicle operator may be present, it may be desirable to periodically conduct a diagnostic test as to whether the active engine mounts are functioning as desired.
The inventors herein have recognized these issues, and have developed systems and methods to at least partially address the above issues. In one example, a method is provided, comprising during propelling a vehicle at least in part by an engine, isolating engine vibration from a cabin and chassis of the vehicle via one or more active engine mounts controllable to a first mode and a second mode; and in a first condition, increasing engine vibrations and controlling the active engine mounts to the first mode and the second mode to diagnose whether the active engine mounts are functioning as desired.
As an example, the method may include providing fuel to one or more engine cylinders via controlling one or more fuel injectors during propelling the vehicle at least in part by the engine; and wherein inducing engine vibrations includes shutting off fueling to a preselected engine cylinder to induce degraded combustion in the preselected engine cylinder.
In one example, the method may include determining whether vibrations stemming from the vehicle cabin and chassis as monitored via one or more vibrational sensors correlate with the increased vibrations during controlling the active engine mounts to the first mode and the second mode during the first condition. The method may thus include indicating the active engine mounts are functioning as desired responsive to monitored vibrations not correlating with increased vibrations in the first mode, but where monitored vibrations are correlated with the increased vibrations in the second mode. In another example, the method may include indicating the active engine mounts are stuck in the first mode responsive to monitored vibrations not correlating with the increased vibrations in the first mode, but where monitored vibrations are correlated with the increased vibrations in the second mode. In still another example, the method may include indicating the active engine mounts are stuck in the second mode responsive to monitored vibrations correlating with the increased vibrations in the first mode, and where monitored vibrations are also correlated with the increased vibrations in the second mode.
As an example, determining whether vibrations stemming from the vehicle cabin and chassis as monitored via the one or more vibrational sensors correlate with the increased vibrations further comprises indicating that the vibrations monitored via the one or more vibrational sensors correlate with the increased vibrations responsive to the monitored vibrations being above a threshold vibration level within a time threshold of the increased vibrations. In this way, a vehicle's active engine mounts may be diagnosed periodically, even under conditions wherein the vehicle is being driven autonomously, for example. By diagnosing the vehicle active engine mounts periodically even under conditions where a vehicle operator may not be present, complications stemming from active engine mounts that are not functioning as desired may be avoided.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.